The following U.S. Patents and Applications provide background information. Each reference is incorporated herein by reference in its entirety.
U.S. Pat. No. 4,050,396 discloses a portable water bailing device including a housing having a plurality of openings therein adjacent the lower end thereof. Within the housing is a water pump connected to a tube for directing the water from the bottom of the boat outwardly over the edges thereof. The water pump is driven by a direct current motor which is connected in series with a battery. Also in series with the battery and motor is a limit switch which is actuated by a float within the housing. As the water rises within the housing, the float actuates the switch which in turn actuates the pump.
U.S. Pat. No. 4,697,515 discloses a marine safety system comprising a first switch adapted to be activated by rising water in a ship's hull, and solenoid valves adapted to be operated by the switch and adapted to close sea cocks in the hull of the ship in a preferred sequence.
U.S. Pat. No. 5,516,312 discloses a device for sensing the presence of hull water above an acceptable level in the hull of a boat and communicating to any combination of ignition, starter, aural and/or visible means in such manner as to cause the boats engine to stop running and apprise the boat operator as to the presence of excessive hull water.
U.S. Pat. No. 7,661,380 discloses an improved bilge water level monitor, alert and control system for boats and other vessels. The system provides a method of detecting excessive leakage of water into the bilge and in response to the excessive water in the bilge, triggering an alarm to notify the operator and others and energizes bilge pumps to remove the excessive water. The system is designed with many redundancies in the sub elements and subsystems for safety. The system provides a means for reducing the likelihood of exhausting battery power in the event of a significant seawater leakage problem. The electrical power rating of the monitoring circuitry components is relatively low, thereby reducing the size and weight of those components relative to prior bilge pump monitoring and alert systems. There is no electrical wiring exposed to bilge water during system operation thereby reducing damage to the wiring components. The water level detection and control circuitry operates with sufficiently low amperage to substantially eliminate the hazard of spark-induced combustion.